Market economics for aesthetic composite structures comprising a substrate and an aesthetic surface layer often favor use of thermosetting resin systems for the substrate. Low raw material and tooling costs are frequently cited as factors supporting selection of thermosetting materials. However, use of thermosetting materials can produce volatile organic compound (VOC) emissions, and generally results in long cycle times.
For example, one commonly used approach for creating aesthetic parts involves a two step procedure, wherein a thermoplastic surface layer is formed using a traditional thermoforming method, a thermosetting material is injected or sprayed behind this surface layer and is cured in-place to create a bi-layered structure having a reinforced sub-layer and a thermoplastic surface layer. Many thermosetting systems and methods are employed to create the reinforced sub-layer. These include, for example, spray-up fiberglass reinforced plastic (FRP), resin transfer molding, vacuum-infusion, and various reinforced foam in-place technologies.
What is needed in the art is a method of making a layered article that produces lower VOC emissions and has a shorter cycle time compared to current methods employing a thermosetting step.